1. Field of the Invention
The present invention relates to an apparatus and method for enabling a wireless local loop (WLL) terminal to process dial signals received from a wire telephone, and more particularly, to a dialing method for recognizing the end of a dialing sequence by detecting a specific key input.
2. Description of the Related Art
A wired telephone, as well as a wireless local loop (WLL) telephone, are connected to a WLL terminal via a tip terminal T and a ring terminal R.
FIG. 1 shows a configuration of a WLL terminal to which a wire telephone (e.g., a public telephone) is connected. The wired telephone requires, in addition to the tip terminal T and the ring terminal R, a subscriber line interface circuit (SLIC) as shown in FIG. 1.
In operation, when a wire telephone 100 is in an off-hook state, the loop current varies. A signal line indicating circuit (SLIC) 25 in a WLL terminal 200 detects the off-hook state of the telephone 100 as a consequence of the change in the loop current. In the off-hook state, if a subscriber dials a telephone number, a dual tone multifrequency (DTMF) signal corresponding to each dialed key is sent to the SLIC 25 via the tip terminal T and ring terminal R connections as shown in FIG. 1. The DTMF signal is supplied from the SLIC 25 to a DTMF receiver 26 where it is converted into a digital signal. A controller 27 temporarily stores the digital signal received from the DTMF receiver 26 in an internal dial buffer 27a. Upon detecting completion of dialing, the controller 27 reads the stored digital signal and supplies the read digital signal to a DTMF generator 27b where a DTMF signal is generated from the received digital signal to be supplied to a radio transmitter/receiver (hereinafter, referred to as an RF (Radio Frequency) circuit 28. The RF circuit 28 modulates the received DTMF signal and wirelessly transmits the modulated signal.
To detect the end of the dialing sequence, a timer is required. After recognizing a single key input, the controller 27 activates the timer and checks whether the next key is input within a prescribed time (e.g., 5 seconds). If there is no key input received within the time interval, it is judged that dialing has been completed.
In the case where the timer is used, a long timer check time may increase a long loop linking time; however, a short timer check time may cause mis-recognition in detecting end of dialing when there is a pause in dialing.